1. Field of the Invention
The present invention relates to a barrel assembly, and more particularly to a barrel assembly for a rivet gun that prevents pneumatic cylinder from outputting high pressure air after an operation of pulling a rivet is completed, which reduces high pressure air consumption.
2. Description of Related Art
A conventional rivet gun is used to rivet two boards such that the boards are securely mounted together by rivets. A rivet has a cap and a core pin. The cap is T-shaped and has an enlarged end and a mounting end. The core pin is mounted longitudinally through and protrudes out of the cap and has two ends and a ball formed on one end and adjacent to the mounting end of the cap.
A conventional rivet gun comprises a barrel, a handle, a trigger, a pin collector and a pneumatic cylinder.
The barrel has a front end, a rear end and a vise assembly that may vise and pull a core pin of a rivet on the front end into the barrel. The handle is mounted perpendicularly on the barrel and has air passageways. The collector is a jar mounted on the rear end of the barrel to collect the ejected core pins. The pneumatic cylinder is mounted movably under the handle and capable of activating the vise assembly through pneumatic and hydraulic means. Furthermore, the pneumatic cylinder may be connected to a high-pressure air source such as an air bottle to implement the ejection of the core pin.
When the rivet gun is used to rivet two pieces such as boards or plates together, a rivet is mounted through the pieces. The enlarged end of the cap of the rivet abuts an inside piece, and the front end of the barrel of the rivet gun abuts the enlarged end. The trigger is pulled to activate the vise assembly to pull a core pin on the cap into the barrel. The ball on the core pin longitudinally compresses and radially expands the mounting end of the cap into T-shape so that the expanded mounting end hooks on an outside piece to complete the riveting process. Then, the air output by the high-pressure air source flows through the barrel from the front end to the rear end and sucks the broken core pin vised by the vise assembly backward into the collector.
Furthermore, a bypass hole is defined through the barrel and communicates with the air passageways. Therefore, when the trigger is pulled, the high pressure air in the pneumatic cylinder passes through air passageways and the bypass hole into the barrel and drives the vise assembly to move backward to pull the rivet.
However, after the vise assembly completes the action of pulling the rivet and stays at a rear position, the pneumatic cylinder continues outputting high pressure air through the bypass hole to external atmosphere, which meaninglessly consumes the high pressure air.
To overcome the shortcomings, the present invention provides a barrel assembly to mitigate or obviate the aforementioned problems.